Regenerative heat exchangers

ABSTRACT

A rotary regenerative heat exchanger having a low speed/high torque motor for driving the rotatable part of the heat exchanger. A rotatable member of the motor is coaxial with and coupled to a trunnion on the rotatable heat exchanger part and stationary motor member is connected to the stationary element of a bearing for the trunnion in order to transfer reaction torque forces to the supporting structure for the bearing.

EUEEQ Pettersson States atent [54] REGENERATIVE HEAT EXCHANGERS [72] Inventor: Birger Pettersson, Alta, Sweden [73] Assignee: Svenska Rotor Maskiner Aktiebolag,

Nacka, Sweden [22] Filed: June 30, 1970 [21] Appl. No.: 51,142

[30] Foreign Application Priority Data July 8, 1969 Great Britain ..34,288/69 [52] US. Cl. ..165/8, 165/68, 248/8 [51] Int. Cl ..F28d 19/04 [58] Field of Search ..165/8, 9, 10, 67, 68; 60/3951; 248/8 [56] References Cited UNITED STATES PATENTS 3,5 87,724 6/1971 Hryniszak ..165/8 1 Aug. 29, 1972 2,893,699 7/1959 Bubniak ..165/9 X 1,762,320 6/1930 Wood ..165/8 X 3,476,173 11/1969 Bracken, Jr. et al ..165/9 Primary Examiner-Albert W. Davis, Jr. Att0rneyBauer and Goodman [57] ABSTRACT A rotary regenerative heat exchanger having a low speed/high torque motor for driving the rotatable part of the heat exchanger. A rotatable member of the motor is coaxial with and coupled to a trunnion on the rotatable heat exchanger part and stationary motor member is connected to the stationary element of a bearing for the trunnion in order to transfer reaction torque forces to the supporting structure for the bearing.

6 Claims, 1 Drawing Figure REGENERATIVE HEAT EXCHANGERS This invention relates to rotary regenerative heat exchangers of the type comprising a matrix unit containing a heat exchanging material and a duct unit for conveying flows of heat exchanging fluids to and from said matrix unit, one of said units being stationary and the other unit being rotatable and provided with trunions at its ends journalled in bearings supported by a supporting structure. Heat exchangers of this type are well known and are for instance commonly used as air preheaters in boiler plants.

During operation the rotatable unit is driven at a very low speed, for instance 2 rpm. Hitherto it has been common practice to drive at least preheaters of larger sizes by means of a suitable electric or hydraulic motor unit at the periphery of the rotatable unit which is provided with a circumferential pin rack. Such pin racks are rather expensive and the meshing between the pinion of the motor and the pin rack undergoes changes during operation due to the thermal deformation of the rotatable preheater unit.

It is also known to drive the rotatable unit at its center by means of a motor through a reduction gear. However, the mounting of the motor and the gear box at one end of the rotatable unit involves severe problems the solutions of which lead to very complicated and expensive structures.

According to the invention a motor for driving the rotatable unit includes a rotatable member coaxial with and coupled to one of said trunnions and a stationary member connected to the stationary part of the bearing for said trunnion in order to transfer reaction torque forces acting upon said stationary motor member to the supporting structure carrying the bearing. The motor is designed to operate at a speed lower than 5 rpm and is carried in its entirety solely by the trunnion and the stationary part of the bearing. This results in a simple design and the reaction torque is transferred to the supporting structure in a very favorable manner. The invention will now be described more in detail with reference applied to an air preheater having stationary ducts for the heat exchanging fluids and a regenerative mass rotatable about a horizontal axis.

Since the invention relates solely to the driving means of the preheater the construction of the latter is shown purely diagrammatically as regards details which are of no interest in this connection.

Numeral 10 indicates the rotatable matrix or rotor carrying the heat exchanging material. The rotor is enclosed in a housing 12 which is provided with an air inlet duct 14, an air outlet duct 16, a gas inlet duct 18 and a gas outlet duct 20. In the drawing the upper portions of the rotor 10, the housing 12 and the gas ducts 18 and 24) are shown cut away.

At each end the rotor 10 is provided with a trunnion 22 which is journalled in a part-spherical roller bearing 24 which is carried by a platform 26 supported by a pedestal formed by two tubular members 28 diverging downwardly from the platform 26 and lying in a plane perpendicular to the rotor axis.

At each side of the housing there is a horizontal beam 30 of substantially U-shaped cross-section. These beams serve to carry the housing 12 and are provided with circular openings 32 to allow passage of the rotor trunnions.

At each end surface of the rotor 10 there is provided in known manner axially movable sector plates 34 extending between the air duct l4, l6 and the gas duct 18, 20 substantially horizontally from the rotor axis. To the beams 30 are secured sealing strips 36 which are in sealing and sliding engagement with the radial edge surfaces of the sector plate 34.

The trunnion 22 at the left side of the rotor 10 is extended beyond the bearing 24 and its free end is coupled to a low speed high torque hydraulic motor 38.

The motor 38 may be of any suitable type but in the embodiment shown there is provided a motor having a rotatable casing part 40 which at its inner side is keyed to the end portion of the trunnion 22 and a stationary inner part 42 protruding through a central opening in a outer end wall of the cylindrical casing 40. The stationary motor part 42 is splined or otherwise nonrotatably connected to a dished annular end wall 44 of a shell structure 46 having a cylindrical portion 48 surrounding the motor 38 and integral with the dished end wall 44 at its outer end. At the inner end of the cylindrical portion 48 there is connected a flat annular end wall 50 the radially inner portion of which is secured to a stationary part or housing 52 of the bearing 24.

The shell structure 46 is shaped as a body of revolution and therefore it is torsionally rigid and capable of transferring high reaction torque forces from the stationary motor member 42 to the stationary part 52 of the bearing 24 from which the forces are transferred to the platform 26 and the pedestal 28. Thus, no separate means are provided for supporting the motor 38 but it is in its entirety carried by the trunnion 22 and the stationary bearing part 52. This involves a simplification and a considerable saving of space.

Since the rotor 10 is very heavy the trunnions 22 during operation may be somewhat deflected. Due to the fact that the annular end walls 44, 50 of the shell structure 46 are rather thin and flexible this deflection has no influence upon the motor members 40, 42.

In the drawing supply and return conduits for the liquid actuating the motor 38 are indicated by numeral 54 and communicate with the interior of the motor 38 are indicated by numeral 54 and communicate with the interior of the motor part 42 at its outer face rendered accessible by the central opening of the annular end wall 44.

The motor 38 may be of any convenient type which can operate continuously at speeds less than 5 rpm while delivering a high torque which, dependent on the dimension of the preheater, may amount to 2,000 kgm or more. Good results have been obtained with a motor of the type which comprises a plurality of pistons moving in radial bores in a stationary block and carrying rollers cooperating at their outer ends with a substantially sinusoidal cam surface on the inside of a drumshaped rotatable outer casing member, such as the member 40.

The invention is not limited to the embodiment shown and described. Further, the invention may also be applied to a heat exchanger having its rotor axis vertical and to heat exchangers having stationary heat exchanging masses and rotatable ducts.

I claim 1. A rotary regenerative heat exchanger comprising:

a matrix unit containing a heat exchanging material;

a duct unit for conveying flows of heat exchanging fluids to and from said matrix unit, one of said units being stationary and the other of said units being rotatable and provided with trunnions at its ends:

beatings, at least one of which has a stationary part,

supported by a supporting structure, said trunnions being journalled in said bearings; and

a motor for driving said rotatable unit including a rotatable member coaxial with and coupled to one of said trunnions, and a stationary member connected to the stationary part of the bearing for said one trunnion through a torsionally rigid shell structure which is substantially shaped as a body of revolution, to thereby transfer reaction torque forces acting upon said stationary motor member to said supporting structure;

said shell structure comprising at least one flexible transversely extending and torque transferring annular wall which compensates for mis-alignment between the axes of said trunnion and said stationary bearing part due to deflection of said rotatable heat exchanger unit.

'2. A heat exchanger as defined in claim 1 in which said motor operates, at a speed lower than 5 rpm.

3. A heat exchanger as defined in claim 1 in which said motor is a hydraulic type motor.

5. A heat exchanger as defined in claim 1 in which said motor has a rotatable casing part and a stationary inner part, said casing part being connected to the end of said trunnion at one side and said inner part being connected to said shell structure at the other side of the casing so that said motor is substantially enclosed in said shell structure 5. A heat exchanger as defined in claim 4 in which said shell structure comprises a cylindrical portion surrounding said motor, an annular end wall connecting one end of said cylindrical portion to said stationary bearing part, and a further annular end wall connecting the other end of said cylindrical portion to the stationary inner part of the motor.

6. A heat exchange as defined in claim 5 in which supply and return conduits for the motive fluid of the motor are connected to said inner motor part uncovered by the central opening of said further annular end wall 

1. A rotary regenerative heat exchanger comprising: a matrix unit containing a heat exchanging material; a duct unit for conveying flows of heat exchanging fluids to and from said matrix unit, one of said units being stationary and the other of said units being rotatable and provided with trunnions at its ends: bearings, at least one of which has a stationary part, supported by a supporting structure, said trunnions being journalled in said bearings; and a motor for driving said rotatable unit including a rotatable member coaxial with and coupled to one of said trunnions, and a stationary member connected to the stationary part of the bearing for said one trunnion through a torsionally rigid shell structure which is substantially shaped as a body of revolution, to thereby transfer reaction torque forces acting upon said stationary motor member to said supporting structure; said shell structure comprising at least one flexible transversely extending and torque transferring annular wall which compensates for mis-alignment between the axes of said trunnion and said stationary bearing part due to deflection of said rotatable heat exchanger unit.
 2. A heat exchanger as defined in claim 1 in which said motor operates at a speed lower than 5 rpm.
 3. A heat exchanger as defined in claim 1 in which said motor is a hydraulic type motor.
 4. A heat exchanger as defined in claim 1 in which said motor has a rotatable casing part and a stationary inner part, said casing part being connected to the end of said trunnion at one side and said inner part being connected to said shell structure at the other side of the casing so that said motor is substantially enclosed in said shell structure.
 5. A heat exchanger as defined in claim 4 in which said shell structure comprises a cylindrical portion surrounding said motor, an annular end wall connecting one end of said cylindrical portion to said stationary bearing part, and a further annular end wall connecting the other end of said cylindrical portion to the stationary inner part of the motor.
 6. A heat exchange as defined in claim 5 in which supply and return conduits for the motive fluid of the motor are connected to said inner motor part uncovered by the central opening of said further annular end wall. 